Coffitdtjir-beubeb



R. H. HENDERSON.

CONDUIT BENDER.

APPLICATION FILED FEB. I9. 1917.

Patented July 15, 1919.

2 SHEETS SHEET 1.

INVEN TOR.

R. H. HENDERSON.

CONDUIT BENDER.

APPLICATION FILED FEB. I9. I9I7.

1,309,849, Patented July 15, 1919.

2 SHEETS-SHEET 2.

1 FIG. 6.

Fla .11. I F1613 2 16213.

WITNESS. JNVENTOR:

ROBERT HALSEY HENDERSON, OF EAST ORANGE, NEW

CONDUIT-BENDEE I l Specification of Letters Patent. Patented uly 15, 1919;

Application filed February 19, 1917. Serial Ho..149,547.

To all whom it may concern Be it known that I, Ronnn'r HALSEY HEN- DERSON, a citizen of the United States, and

a resident of East Orange, county of Essex,

kinds, and particularly to the bending of conduit for electrical purposes.

The bending of conduit or tubing sets up two separate molecular changes in its structure; on the outside of the bend the tendency is-to make the wall of the tubing thinner, or stretch it; while on the inside of the bend the tendency is to make the wall of the tubing thicker, or upset it. If the bend is made all at one operation, the tubing will .invariably flatten or kink except in the smaller sizes in which the thickness of'the wall in its relation to the diameter is proportionately much greater than in the larger sizes. The reason for this flattening is that in cases where a considerable bend is attempted at one operation on the larger sizes of conduit, proper support cannot be given to the conduit to gradually knead, compress and otherwise mold it into the desired shape.

I have discovered certain facts, and evolved certain principles with regard to the bending of pipe and conduit without preheating, which are as follows: Pressure should always be applied in line with the center of the conduit; Conduit should be bent betweentwo bosses or their mechanical equivalent. The holding boss under which the end of the conduit is placed may or may not be grooved, if the boss has suflicient I length of holding surface it will not kink the pipe even if the boss is perfectly flat. The nding boss, on the other hand, must be accurately grooved to fit the particular size of conduit to be bent, if the best results areto be obtained, and the sides of the groove must be high enough to grip the sides of the conduit when it tends to spread during the bending operation. This latter feature is of major importance as it prevents the conduit from slipping by gripping the s des of the bender groove, and does away with the necessity of clamping one end of the conduit in a vise, or otherwise securing it, while the bend is made. In addition, a properly shaped, deep groove keeps the conduit from flattening, which flattening is a very serious defect as it renders it difficult and sometimes impossible to draw in'wires or cables. The working surface of the bending boss, which surface contains the groove before mentioned, must be curved, and the radius of the curve at thebottom of the groove must be less than the radius of the standard conduit elbow for the particular size conduit that is to be bent. Proper elbows cannot be bent on a boss with a radius as large as that of elbow, as the conduit has to be bent slightly more.

gree elbow on account of the spring of the metal. To produce the most satisfactory results, the bosses should be so located that the conduit is introduced between them at an angle, and the distance from the holding boss to the point of bending contact in the bottom of the groove on the bending boss should be slightly more than the diameter of the conduit. With such an arrangement the conduit is placed between the bosses, pressure is applied to the conduit on the end away from the bending boss, and the conduit is given a definite set, that is to say therbend is just started, it is then advanced about3/32 or '1/ and the operation repeated, this bending by easy stages is continued until the desired bend is obtained, even to a complete circle; My method does not kink or flatten the conduit, but gradually eratum, and I believe that my invention as hereinafter described is as far as I know the only one that will produce the desired result ina perfectly satisfactory and workmanlike manner.

The object of my invention is to produce conduit benders which shall bend conduit by easy, and successive stages, without kinking or flattening, or slipping, accurately to predetermined dimensions, and to any desired angle or succession of angles and ofisets required for the installation of electrical conduit. l

form of my bender, showing a conduit in the process of being bent; Fig. 2 is a right hand end view of Fig. 1; Fig. 3 is a left hand view of Fig. 1; Fig. 4 is afront view of a bender with a revoluble forming member; Fig. 5 is a right hand end view of Fig. 4; Fig. 6 is a left hand end view of Fig. 4; Fig. 7 is a front view of a bender with detachable forming members; Fig. 8 is a right hand end view of Fig. 7 Fig. 9 is a left hand end view of Fig. 7; Fig. 10 is an edge elevation of Fig. 7; Fig. 11 is a side view of a forming member for bender shown in Fig. 7; Fig. 12 is an end view of the forming member shown in Fig. 11; Fig. 13 is a front "iew of a forming member for Fig. 7 reversibly mounted. Fig. 14 is a transverse sectional view, in the nature of a diagram, showing, in solid lines, a pipe located in the combined forming, and holding member, and, illustrating in dotted lines, the shape whichthe pipe assumes at the spot where the bending is taking place, while being bent.

Similar numerals refer to similar parts throughout the several views.

In Fig. 1, 14 is a sectionor broken length of conduit which is shown as being in proc ess of bending between theholding member 15 and the forming member 16, members 15 and 16 being preferably integrally formed with the base plate 17. Holes 18 18 are drilled to snugly fit mounting bolts, and being located at the points of greatest strain in the members 15 and 16, said mounting bolts serve to greatly strengthen these members and at the same time hold the bender in position on a post or other suitable support notshown. Holding member 15 has a groove 19 in its working face. This groove is useful in causing the conduit to center in the bottom of the groove, but it is not required in preventing the conduit from flattening. Bending member 16 has a deep groove 20, said groove being accurately shaped to exactly fit the particular size of conduit for which the bender is designed, with the sides high enough, generally considerably above the center of the conduit, to prevent the conduit from kinking and also to rip the sides of the conduit and prevent it from slipping when it spreads slightly as it will, when it is being bent over the forming member 16. -Throughout the different drawings'it is to be understood that the holding downward against the member 16, and into the groove 20, which groove is curved as shown and on a smaller radius thanthe bend desired in the conduit to compensate for the spring in the metal. Conduit 14 is shown ready to receive an additional bend, after which operation it will assume in general, the

position indicated by the dotted lines Fig. 1.-

As the conduit 14 is advanced by easy stages, and bent still more between the members 15 and 16, it is held in each new position by the holding member 15 and by being wedged in the groove 20, caused by its slight spreading during the bending operation, until the desired curvature is obtained.

Figs. 4, 5, and 6 show a bender with a base plate 17, and four holes for mounting bolts 21, a reversible bending member 22, having four accurately fitting curved grooves 20, for four different sizes of conduit, the holding member 23, having a suitable holding surface 24. Bolt 25 passes through base plate 17, revoluble bending member 22, and

washer 26, nut 27serving to tighten them all in place. A rib or projection 28 is integrally formed on the back of member 22, and is located on a line passing through the axis of revolution which is identical with thelocation of the bolt 25, recess 29 in base plate 17 is adapted to receive rib or projection 28, and the two combined, together with bolt 25, serving to keep member 22 fixedly in a given position.

Figs. 7, 8, 9, 10, 11, 12, 13, illustrate a combination bender and details of same, with the same working and operating characteristics as those disclosed in connection with Figs. 1 and 4. Base plate 17 is adaptedto as it is being bent between the members 15 and 31. Holding member 15 with holding surface 19 is preferably'integrally formed on base plate 17. Supporting bracket 32, for detachable bending members 31 and 33, may be integrally formed with the base plate 17, or may be mounted thereon. Bending members 31 and 33, are detachable as shown, being bolted to supporting bracket 32, by means of bolt 34, passing through bracket 32, washer 35 and held by nut 36. Only two sizes of the bending members (31 and 33) are shown, but it is understood that bending members for all sizes can be mounted on supporting bracket 32. Bending members 31 and 33 have grooves which are constructed to accurately fit the conduit of the particular size for which they are designed, with deep grooves to prevent flattening of the conduit, said grooves fitting the sides of the conduit so closely that the lateral distortion incident to bending is suflicient to firmly hold the conduit and prevent it from slipor the other of the opposing margins o supporting bracket 32.

Fig. 7 is an assembled view showing bending member 31 in position. This bending V duit.

member 31 can be replaced, for instance, by bending'member 33, shown in Figs. 11 and 12, by removing the nut 36 and lifting off the member 31, replacing it with member 33. or with a member having a groove and curved bending surface suitable for still another size of conduit. Fig. 8, shows bending member 31, suitable for a small size of conduit in its working position, and Fig. 9, shows the contour of the her 15.. Fig. 10 shows the bolt 34 for member 31, and holding member 15 with groove 19. Figs. 11 and 12, show the details of bending member 33, while Fig. 13, shows a reversible mounting of the bending members; in this case member. 31 is shown, but thisv reversibility for special bending is applicable to the various sizes of bending members required for the different sizes of con- Attention is now directed to the, fact that the differentiating feature of my invention from others, resides in a base plate having a forming, and a retaining member spaced apart a short-distance but suificiently so, and onlyso, as to permit a pipe from being placed onto, and removed from, the apparatus sidewise, and that the forming member has arcuate curves of a lesser radius than that of the closest elbow that .can be bent on a given size pipe, .and grooves closely fitting the pipe tobe bent, but not enough so, to prevent the pipe from being moved in said groove, whereby, when a pipe is mthe act of being bent, the natural spreading ofthe pipe between the walls of the groove, is made available to cause the pipe to be tightly wedged in the groove. This slight spreading of the pipe is not suflicient to permanently set the pipein its newly-acquired form, so that, when the force applied to the pipe to bend it, when released, the

pipewill again'resume its normal molecular condition, caused bythe resiliency and elasticity of the metal of the pipe, so that the pipemay be again moved in the groove, per

' mitting an interval of time to elapse durlng which the molecular condition for the pipe, disturbed by the bending operation, may resume normal condition. It is compara tively easy to bend and inch pipe, and probably g inch, withoutany Special form, or prior preparation, or withhand-benders, but 1, 1i, and larger pipe cannot be groove 19 in the holding mem- V satisfactorily bent cold on any bender withwhich I am' acquainted without more or less flattening and spreading at the bent portion, even when the pipe is preheated or filled with an elastic medium, unless the bending is done by my method of bending in successive stages, with a short interval between successive bendings to permit the original molecular condition of the metal to be restored, and on forms which 'fit the particular pipe so closely that whatever slight spreading of the pipe may be permitted to cause the-pipe to be tightly wedged in the groove, is not suflicient to disturb the elastic and resilient condition of the metal of the pipe. This is the all-important feature of my invention, and accounts for my success in bending pipe cold in a mannersuperior to any other now being practised, as far as I am aware, having devoted many years of time to develop the art of pipe bending and the conduit after a bent portion of. the conduit reaches this member 15. I have, there fore, employed in'the claim the term abutment to designate this holding boss by. what I believe to be a more suitable term.

And while the member 16 is a forming boss, it performs the additional function of being a holding member, inasmuch as the pipe, while being bent, istightly wedged between the parallel members or walls. of the open, arcuate, groove 20, in'this member 16, caused by the slight'spreading of the conduit at the spot therein where the bending takes place.

This condition I have illustrated in Fig..

14, wherein the pipe 14 is shown in dotted lines in the temporarily deformed condition, the deformation being slightly exaggerated,

and which deformation, in reality, is not.

sufiicient to permanently set the conduit in its deformed condition, because the resiliency and elasticity of the metal will cause it to resume its normal condition as soon as the downward pressure on the conduit is released. I, therefore, prefer to term this member 16 in the claim, acombined forming and holding member, a term which I believe will more accurately define the mem-- ber 16, and its functions.

' While I have described several benders, I do not desire to limit myself to the particular constructions as set forth, but claim the right to make substitutions of equivalents in form and structure to meet the varying demands arising in practice.

I claim:

A pipe bending device, comprising a substantially square base plate, there being in said base plate bolt holes for attachment of said base plate to a support, an open, hook-shaped abutment on said base plate, said abutment being located at one corner of said base plate and integrally formed therewith, a bracket extending from said base plate and integrally formed there- With, said bracket having medially a vertically disposed bolt hole, a forming member, said forming member being located upon the upper surface ofsaid bracket and secured thereto by a bolt, said bolt being secured to said holding member and passing through the hole in said bracket, said forming member having an arcuate groove of varying radii, said groove being deeper than the radius of the pipe to be bent, said groove fitting said pipe by a close, sliding, fit, said pipe While being bent, being permitted to expand to Wedge itself in said groove, and to be movable in said groove after recovering its normal condition.

In testimony that I claim the foregoing as my invention, I have hereunto set my hand. a

ROBERT HALSEY HENDERSON. 

